The Clinical Neurogenetics Unit research program is focused on identification and characterization of genes and genetic mechanisms involved in hereditary a) movement disorders, b) neuromuscular disorders, and c) prion diseases. Major findings: A clinically and pathologically distinct type of cardioskeletal myopathy is associated with mutations in the desmin gene: sixteen causative mutations have now been identified and described, and adverse effects of each mutation tested in a cell culture expression system. An extremely aggressive variant of malignant hyperthermia was characterized in large North and South American families and linked to a novel mutation in the ryanodine receptor (RYR1) gene. A new study shows that worldwide distribution of hereditary Creutzfeldt-Jakob disease/Fatal Insomnia associated with the PRNP D178N mutation depends on recurrent mutations rather than founder effect. Genetic susceptibility to kuru and new variant Creutzfeldt-Jakob disease is tightly linked to a M/V polymorphism in the PRNP gene, providing a model for predictions of the length and size of the developing epidemic of variant CJD associated with mad cow disease. Tremor-dystonia type of essential tremor in a large American family is shown to be linked to a 7cM locus on chromosome 6p. Evidence is presented that a herpesvirus caused a large epidemic of Viliuisk encephalomyelitis in a limited area of Eastern Siberia.